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Industrial environments

Making the connection to industrial serial devices

Serial servers enable you to use your network to connect to serial devices over very long distances—as far as your network stretches. It’s even possible to control serial devices across the Internet. Serial servers act as virtual serial ports by providing the appropriate connectors for serial data and also by grouping serial data in both directions into Ethernet TCP/IP packets. This enables you to control serial devices across Ethernet without the need for software changes.

Industrial serial interfaces

Industrial control is a designation for the devices that interface with machinery such as welders, mixers, generators, lathes, and packaging machines. Although most of today’s IT runs on Ethernet, industrial devices often use an RS-232, RS-485, or RS-422 serial interface.

RS-232 is a group of electrical, functional, and mechanical specifications for serial interfaces. It transmits data at speeds up to 115 kbps and over distances up to 15m, although higher distances can be achieved by using special low-capacitance cable. Both sync and async binary data transmission fall under RS-232. Although the original RS-232 connector is DB25, DB9 and RJ-45 connectors are now common. Also, industrial devices often use a terminal block instead of a connector for the RS-232 interface. RS-232 is somewhat restricted as an industrial interface because of its restricted range and because it only supports point-to-point links.

The RS-422 supports point-to-point and multidrop applications at distances of up to 1200 metres. Up to 32 listening devices can be connected to and controlled from a single RS-422 port.
RS-485 is similar to RS-422 but supports multiple commanding devices as well as multiple listening devices at distances of up to 1200 metres.